Comey says Trump's lying, Trump says Comey's lying

President Donald Trump says he's "100 percent" willing to testify under oath about his interactions with fired FBI director James Comey.

Mr Comey, who was fired by Mr Trump in May, delivered a scathing indictment of the president on Thursday at a congressional hearing. He accused Mr Trump of trying to block the investigation into fired National Security advisor Michael Flynn.

Mr Comey also said Mr Trump asked him in January to pledge loyalty to the President, an unusual request that would put in doubt the independence of the FBI.

"I hardly know the man. I'm not going to say I want you to pledge allegiance. Who would do that?" Mr Trump has told local media.

But the former FBI boss told the Senate panel he took meticulous notes of each meeting or conversation he had with Mr Trump because "I was honestly concerned that he might lie about the nature of our meeting, and so I thought it really important to document".

Mr Trump wouldn't rule out a previous claim that there may be tapes of his conversations with Mr Comey.

"Well, I'll tell you about that maybe sometime in the very near future," he told local media.

Mr Comey has been asked to provide any notes or memoranda related to discussions with President Donald Trump, to the ongoing investigation into Russia's involvement in the election.

The leaders of the House of Representatives intelligence committee said on Friday they've written to Mr Comey.

Republican Representative Mike Conaway and Democratic Representative Adam Schiff said they had also written to Don McGahn, the White House counsel, and asked him whether White House recordings or memos of Mr Comey's conversations with Mr Trump exist.

If they do, they asked that copies of the materials be provided to the panel by June 23.